Robert M. knew something was wrong when his 1-year-old cat, Kitty, began vomiting and stopped eating. But what he didn’t know was that Kitty had somehow swallowed a penny.

Earlier this month, Robert drove Kitty from his home in Bellmore, Long Island to the ASPCA Animal Hospital in Manhattan. X-rays revealed what looked like a shiny penny lodged in Kitty’s small intestine, having already passed through her stomach.

“It was the worst day ever,” says Robert. “She is such a wonderful cat and she was just so sick.”

Dr. Anna Whitehead, who performed surgery on Kitty the same day, has retrieved coins from dogs in the past, but says it’s rare for cats to swallow loose change.

She also says Kitty was lucky her condition was not worse, because of the penny’s composition.

Pennies dated before 1982 are made of 95 percent copper, and those dated 1983 or later are made of 97.5 percent zinc and coated in a thin plate of copper. The cent's composition was changed in 1982 because the value of the copper in one cent pieces rose above one cent.

“Stomach acid corrodes pennies made of zinc and can cause hemolysis, or a rupturing of red blood cells that leads to life-threatening anemia,” says Dr. Whitehead.

In Kitty’s case, the penny had turned black from corrosion, making the 1986 mint date barely legible.

“It’s hard to say what happened or how long it had been in there,” says Dr. Whitehead.

As for the penny, it won’t turn up again. Robert is keeping it as a reminder of Kitty’s ordeal and has taken it out of circulation.